Hi. I don’t know if you’ve seen this reaction to a 300 amp showing up, but it might be food for thought…
The reality is what we all know and pretend doesn’t happen, namely that upgrading is almost limitless and whatever you might think is the final piece in the jigsaw, it just opens up a whole new set of permutations.
Slightly off topic but hopefully relevant to the OP.
The 555 ps seems to transform everything. The XPS has very mixed reviews.
Could the quality of your mains (eg dedicated mains, lower levels of pollution etc) influence how effective the XPS is on your source. If you have a poor mains supply the XPS works well and Vice Versa.
Obviously the 555 is that good matters not the quality of the mains, you will hear a difference??